Stimulation device and method for transcutaneous electrical stimulation

ABSTRACT

A device for transcutaneous electrical stimulation is provided. The device comprises circuitry configured to generate transcutaneous stimulation signals. The device also comprises a first signal output component for electrically connecting to a first electrode connector to deliver generated transcutaneous stimulation signals. The first signal output component comprises a first four-pole electrical connector part. The device further comprises a second signal output component for electrically connecting to a second electrode connector to deliver generated transcutaneous stimulation signals. The second signal output component comprises a second four-pole electrical connector part. The device further comprises a controller to selectively control output of the stimulation signals to selected pairs of poles across the first and second four-pole electrical connector parts. Each selected pair of poles comprises one pole from the first four-pole electrical connector part and one pole from the second four-pole electrical connector part.

TECHNICAL FIELD

Described embodiments generally relate to methods and systems fortranscutaneous stimulation. In particular, described embodiments aredirected to methods, devices and systems for transcutaneous stimulationin the lumbar and/or abdominal region to treat one or more dysfunctionsassociated with a body's ability to evacuate waste.

BACKGROUND

Waste elimination dysfunction of the gastrointestinal tract can takemany forms. For example, intestinal incontinence or constipation canoccur. Treatment systems exist for treating constipation by providingelectrical stimulus via subcutaneously implanted electrodes positionedaround the lower bowel. Electrical stimulation provided using suchelectrodes can be used to sequentially activate muscle fibres around thebowel to force a peristaltic action to occur. However, such treatmentsystems are undesirably invasive. Further, while such systems may havean immediate effect in assisting to evacuate the bowel, they do notnecessarily address the cause of the constipation. Importantly, thiseffect has not been described as long lasting, or having an effectbeyond the immediate time of electrical stimulation.

Intractable constipation and soiling are extremely common in thecommunity, in both the young and the old, and available treatments aregenerally uncomfortable, can cause social distress for sufferers and area significant drain on the health care system. Individuals that sufferfrom constipation and soiling who are young or old may also havepsychological issues. In addition, constipation may be a side effect ofsome kinds of medication, such as opiates. Most laxative therapies aredesigned to either soften the stool or stimulate the bowel by chemicalsin the lumen. Patients with chronic constipation or intractableconstipation may have failed other treatment methods includingpharmaceutical treatment. Patients on therapies for other diseases inwhich constipation is a side effect of the medication may not be able tobe co-administered pharmaceutical treatments for constipation.Non-invasive, non-drug-based treatment methodologies may be desired insome cases.

Sometimes constipation may be unrelated to diet or medications, and canbe due to poor motility in the whole colon. A newly identified disorder,which is known as slow-transit constipation (STC), is not uncommonamongst children who fail standard medical therapy, and such childrenoften have signs of colonic dysfunction even at birth.

Some devices exist for delivering transcutaneous stimulation and/ortreating faecal waste evacuation dysfunction. However, various drawbacksexist with such devices.

It is desired to address or ameliorate one or more shortcomings ordisadvantages or shortcomings associated with existing faecal wasteevacuation treatment devices, systems, methods or regimes, or to atleast provide a useful alternative thereto.

Any discussion of documents, acts, materials, devices, articles or thelike which has been included in the present specification is not to betaken as an admission that any or all of these matters form part of theprior art base or were common general knowledge in the field relevant tothe present disclosure as it existed before the priority date of eachclaim of this application.

Throughout this specification the word “comprise”, or variations such as“comprises” or “comprising”, will be understood to imply the inclusionof a stated element, integer or step, or group of elements, integers orsteps, but not the exclusion of any other element, integer or step, orgroup of elements, integers or steps.

SUMMARY

Some embodiments relate to a device for transcutaneous electricalstimulation, comprising:

-   -   circuitry configured to generate transcutaneous stimulation        signals;    -   a first signal output component for electrically connecting to a        first electrode connector to deliver generated transcutaneous        stimulation signals, the first signal output component        comprising a first four-pole electrical connector part;    -   a second signal output component for electrically connecting to        a second electrode connector to deliver generated transcutaneous        stimulation signals, the second signal output component        comprising a second four-pole electrical connector part; and    -   a controller to selectively control output of the stimulation        signals to selected pairs of poles across the first and second        four-pole electrical connector parts, wherein each selected pair        of poles comprises one pole from the first four-pole electrical        connector part and one pole from the second four-pole electrical        connector part.

Some embodiments relate to a device for transcutaneous electricalstimulation, comprising:

-   -   circuitry configured to generate transcutaneous interferential        current stimulation signals;    -   at least one first signal output component for electrically        connecting to a first bank of stimulation electrodes; and    -   at least one second signal output component for electrically        connecting to a second bank of stimulation electrodes; and    -   wherein the device is configured to deliver generated        transcutaneous interferential stimulation signals to the first        bank for a first set period of time, and subsequently to the        second bank for a second set period of time when the first and        second signal output components are electrically connected to        the respective first and second banks of the stimulation        electrodes.

The transcutaneous stimulation signals may comprise interferentialcurrent stimulation signals for application to a front body regionincluding the lower abdomen and pelvic area and a back body regionincluding the lumbar and sacral area. The first and second signalcoupling components may each define respective sockets for receiving amating jack of respective electrode connectors and for transmittingstimulation signals across a set of channels. In some embodiments, theremay be at least two channels. In some other embodiments, there may be atleast four channels.

The device may be substantially free of external user operatablecontrols other than a means of turning the device on an off, a means tocontrol the intensity of the transcutaneous stimulation signals, and ameans to turn on and off a sound generating component.

The device may comprise communication circuitry configured to allowcommunication with an external computing device. The device may beconfigured to allow configuration of electrical stimulation parametersof the device by the external computing device via the communicationcircuitry. The electrical stimulation parameters may include: a maximumcurrent intensity setting to be applied in the transcutaneous electricalstimulation; a duration of transcutaneous electrical stimulation; and asequence of electrode pairs to which the transcutaneous electricalstimulation is to be applied.

The device may further comprise isolation circuitry to electricallyisolate a power supply unit of the device from the signal outputcomponents. The device may further comprise a microcontroller, a memoryunit and at least one user interface component.

The device may be configured to deliver the transcutaneous electricalstimulation according to at least one stored configuration parameterstored in the memory unit. The device may be configured so that, whencommencing the transcutaneous electrical stimulation, the current of thestimulation is initially zero and is automatically increased over timeuntil it reaches a pre-set stimulation level or is stopped by user inputand can then be modified by user input.

The device may be configured to monitor an impedance between pairs ofoutput terminals of the first and second signal output components, andto produce a pad fault signal when the impedance is above apredetermined threshold level.

The device may further comprise means to generate at least one ofvisual, aural, and tactile notifications.

Some embodiments relate to a method performed in a device configured togenerate transcutaneous interferential current stimulation for deliveryto a first set of at least four electrodes on a front of a torso and asecond set of at least four electrodes on a back of the torso, themethod comprising:

-   -   selecting two pairs of electrodes, wherein each selected pair of        electrodes comprises one electrode from the first set of        electrodes and one electrode from the second set of electrodes;    -   delivering transcutaneous stimulation signals to the selected        electrodes from the first set of electrodes; and    -   at the same time as delivering transcutaneous stimulation        signals to the selected electrodes from the first set of        electrodes, delivering transcutaneous interferential current        stimulation signals to the selected electrodes from the second        set of electrodes.

Some embodiments relate to a stimulation device for transcutaneouselectrical stimulation, comprising:

-   -   a housing having a first end and an opposite second end;    -   circuitry configured to generate transcutaneous stimulation        signals; and    -   first and second signal coupling components for connection to        respective electrode connectors to deliver the transcutaneous        stimulation signals;    -   wherein each of the first and second signal coupling components        is located at the first end of the housing, wherein the first        signal coupling component has a first coupling axis and the        second signal coupling component has a second coupling axis, and        wherein the first and second coupling axes are disposed at an        angle relative to each other.

The angle may be between about 120° and about 60°. The angle may bebetween about 100° and about 80°. The angle may be about 90°.

The housing first end may comprise first and second opposed cornerportions and first and second coupling axes extend through the first andsecond corner portions. The first and second corner portions may definerespective recesses for receiving at least a part of respectiveelectrode connectors.

Some embodiments relate to a stimulation device for transcutaneouselectrical stimulation, comprising:

-   -   a housing having a first end and a second end;    -   a screen display;    -   circuitry configured to generate transcutaneous stimulation        signals;    -   first and second signal coupling components for connection to        respective electrode connectors to deliver the transcutaneous        stimulation signals, the coupling components being at the first        end; and    -   a coupling portion, to couple the device to a wearer, the        coupling portion being connected to the housing at the first        end;    -   wherein the coupling portion allows the device to hang in an        inverted position in which the display is upside-down so that        when the second end of the device is pivoted upwardly away from        the wearer, the display is right-side-up from the wearer's        perspective.

The first signal coupling component may have a first coupling axis andthe second signal coupling component may have a second coupling axis,and first and second coupling axes may be disposed at an angle relativeto each other.

The angle may be between about 120° and about 60°. The device mayfurther comprise user controls at the second end. The coupling portionmay comprise a clip.

The coupling portion may cooperate with a receiving portion of anelectrode carrier to allow the device to be pivoted so that the secondend can be swung from below the first end upwards and away from the bodyof the wearer.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments are described in further detail below, by way of example andwith reference to the accompanying drawings, in which:

FIG. 1 shows a front view of a stimulation device according to someembodiments;

FIG. 2 shows a stimulation system including the stimulation device ofFIG. 1;

FIG. 3 shows a block diagram of the electrical components of thestimulation device of FIG. 1;

FIG. 4 shows a block diagram of the firmware components of thestimulation device of FIG. 1;

FIG. 5 shows a block diagram of the application threads andinter-process communication of the firmware of the device of FIG. 1;

FIG. 6 shows a state diagram illustrating the system states of thedevice of FIG. 1;

FIG. 7 shows a flow chart diagram illustrating the functions of thestimulation device of FIG. 1;

FIG. 8 is a sequence diagram of a power-up initialisation sequence forthe firmware of the device of FIG. 1;

FIG. 9 is a sequence diagram of a host communication mode sequence forthe firmware of the device of FIG. 1;

FIGS. 10a and 10b are sequence diagrams of a set device configurationsequence for the firmware of the device of FIG. 1;

FIG. 11 is a sequence diagram of a read device configuration sequencefor the firmware of the device of FIG. 1;

FIG. 12 is a sequence diagram of a clear treatment records sequence forthe firmware of the device of FIG. 1;

FIG. 13 is a sequence diagram of a treatment reporting sequence for thefirmware of the device of FIG. 1;

FIG. 14 is a sequence diagram of a firmware upgrade sequence for thefirmware of the device of FIG. 1;

FIG. 15 is a sequence diagram of a charging sequence for the firmware ofthe device of FIG. 1;

FIG. 16 is a sequence diagram of a charging in host communications modesequence for the firmware of the device of FIG. 1;

FIG. 17 is a sequence diagram of a charging during treatment sequencefor the firmware of the device of FIG. 1;

FIG. 18 is a sequence diagram of a treatment sequence while charging forthe firmware of the device of FIG. 1;

FIG. 19 is a sequence diagram of a treatment sequence during hostcommunications for the firmware of the device of FIG. 1;

FIG. 20 is a sequence diagram of a low battery sequence for the firmwareof the device of FIG. 1;

FIG. 21 is a sequence diagram of a final configuration sequence for thefirmware of the device of FIG. 1;

FIG. 22 is a sequence diagram of treatment cycle sequence for thefirmware of the device of FIG. 1;

FIG. 23 is a sequence diagram of pad fault detection sequence for thefirmware of the device of FIG. 1;

FIG. 24 is a sequence diagram of adjustment during treatment sequencefor the firmware of the device of FIG. 1;

FIG. 25 is a sequence diagram of interrupted treatment sequence for thefirmware of the device of FIG. 1;

FIG. 26 is a sequence diagram of end of treatment indication sequencefor the firmware of the device of FIG. 1;

FIG. 27 is a sequence diagram of scrolling text message sequence for thefirmware of the device of FIG. 1;

FIG. 28 is a sequence diagram of device fault detection sequence for thefirmware of the device of FIG. 1;

FIG. 29 is an example client-side display of a patient data calendarview page of an application running on the computing device of FIG. 2;

FIG. 30 is an example client-side display of a patient data graph viewpage of an application running the computing device of FIG. 2;

FIG. 31 is an example client-side display of a treatment settings pageof an application running on the computing device of FIG. 2;

FIG. 32 is an example client-side display of a device setup page of anapplication run on the computing device of FIG. 2;

FIGS. 33a and 33b show top and perspective views of connectors that mayplug into some embodiments of the device of FIG. 1;

FIG. 34 is a diagram illustrating signal path channels of the device ofFIG. 1;

FIGS. 35a, 33b and 35c show top, perspective and end views of analternative connector that may plug into some embodiments of the deviceof FIG. 1;

FIG. 36a shows a perspective side view of the device of FIG. 1; and

FIG. 36b shows a back view of the device of FIG. 1.

DETAILED DESCRIPTION

Described embodiments generally relate to methods and systems fortranscutaneous stimulation. In particular, described embodiments aredirected to methods, devices and systems for transcutaneous stimulationin the lumbar and/or abdominal region to treat one or more dysfunctionsassociated with a body's ability to evacuate waste, in particular wasteassociated with disorders of the gastrointestinal tract.

Described embodiments generally relate to improvements and furtherdevelopments to embodiments described in earlier International PatentApplication PCT/AU2012/000212, published as International PatentPublication No. WO 2012/116407, the entire contents of which are hereinincorporated by reference. International Patent Publication No. WO2012/116407 discusses various methods and regimes for treating a wasteevacuation dysfunction by administering transcutaneous electricalstimulation (TES) to a patient. In some embodiments, the stimulationgeneration device 100 described herein is configured to generate andtransmit transcutaneous electrical stimulation in accordance with theteachings of WO 2012/116407 to treat a waste evacuation dysfunction. Forexample, the stimulation generation device 100 may be configured toprovide a stimulation current across a 1 KΩ load with a peak-to-peakmagnitude of less than about 40 mA and greater than zero mA. The currentmay be provided at a carrier frequency of between about 1 kHz and about10 kHz, with a modulated frequency of about 20 Hz to about 300 Hz.Alternatively, the carrier frequency may be about 4 kHz and themodulated frequency may be about 80 Hz to 150 Hz, or 80 Hz to 160 Hz insome embodiments. Furthermore, the electrical stimulation may compriseinterferential electrical current stimulation.

In some embodiments, the stimulation generation device 100 may beconfigured to provide transcutaneous electrical stimulation to first andsecond electrode connector assemblies 220, 230 for at least onetreatment period per day over a treatment term of at least one week,and/or for two or three treatment periods per day. In some embodimentsthe treatment period may be between about 10 minutes and about 90minutes, or between about 20 minutes and about 60 minutes.

FIG. 1 shows a stimulation device 100 according to some embodiments.Described embodiments of device 100 are generally directed towards theuse of the device to drive stimulation signals onto electrode connectorsfor electrical communication of the signals to electrode pads that areto be worn on the body of a patient, for the treatment of one or moredysfunctions associated with a body's ability to evacuate waste, inparticular disorders associated with waste evacuation of thegastrointestinal tract.

In some embodiments, the device 100 is used in a method of treatment offaecal evacuation disorders, such as and not limited to: constipation,slow transit constipation, functional faecal retention, rectalfaecalomas, anal retention or irritable bowel syndrome withconstipation, for example.

Stimulation device 100 comprises a housing 105 with a top end 110, abottom end 120, and a display portion, which may be a screen such as LCDsegment display screen 130 or a touch screen. In some embodiments,screen 130 may be a standard LCD screen, such as a 4.8″ colour LCDscreen, for example. Top end 110 and bottom end 120 extend along, andare positioned at opposite ends of, a long axis of the housing 105. Thehousing 105 houses internal components of the device 100, such as itselectronics and other components, as described further below.Stimulation device 100 may further include other outputs, such as aspeaker or piezoelectric buzzer to produce sound, or a motor to providetactile vibration to the user. Stimulation device 100 may also haveinputs such as accelerometers, GPS modules, microphones or cameras.Stimulation device 100 may be a handheld device generally of a size andshape easily held in one hand of the user. The device 100 may further belightweight and robust, with the exterior being of a smooth constructionwith few sharp edges or projections. The device 100 may generally bedesigned for easy portability and handling.

Screen 130 is configured to be human-readable when stimulation device100 is oriented such that top end 110 is (from the viewer's perspective)above bottom end 120. Stimulation device 100 has connector inputs 160and 165 located at and extending within corner portions of bottom end120, and may be configured to deliver stimulation signals to electrodeselectrically coupled to the connector inputs 160 and 165 (e.g. byconnector jacks 224, 234 shown in FIG. 2). In some embodiments,connector inputs 160 and 165 may be positioned at an angle of about 90°to each other. The connector inputs 160 and 165 may respectivelycomprise sockets to receive respective connector jacks 224, 234 and thehousing 105 may define recesses (not shown) at the corner portions ofbottom end 120 within which the sockets extend inwardly of the housing105. Plastic moulded end parts of the jacks can be at least partiallyreceived within the recesses. This configuration reduces the risk of theconnector jacks coming loose from connector inputs 160 and 165 due tohorizontal or vertical strain when the device is worn on the patient'sbody in the “upside-down” orientation where top end 110 is below bottomend 120.

In some embodiments, connector inputs 160 and 165 may be positioned atanother angle to each other, such as an angle of between about 120° andabout 60°, or of between about 100° and about 80°. In some embodiments,the angle may be about 90°. In some embodiments, the connector inputs160 and 165 may be positioned at the corners of the bottom end 120 ofdevice 100.

Stimulation device 100 may further include a clip 195 (see FIGS. 36a and36b ) that attaches to a belt or waistband of the user. In someembodiments, the clip may be a loop of wire that extends from bottom end120 partly down the length of the body of device 100 and back to bottomend 120. The belt may be any conventional belt, or a belt specificallydesigned to hold stimulation device 100. The waistband may be awaistband of a garment such as a pair of pants or shorts, or a skirt. Insome embodiments, another means of attachment to the body of a patient,or to a garment worn on the body of a patient, may be used. This may bea means of attachment to the patient's belt, waistband, or othergarment. In some embodiments, the means may include multiple strips ofmating Velcro, a series of snaps or buttons. Alternatively, the means ofattachment may be a specially-designed belt or holster including acustom pocket designed to receive stimulation device 100 or clip 195.When the device is worn on the body of a patient, the device may be wornsuch that top end 110 hangs below bottom end 120. When worn in this way,device 100 hangs in an orientation where screen 130 is upside-down (withtop end 110 below bottom end 120) and facing away from the body of theuser.

To read screen 130, the user can flip device 100 upward about a pivotpoint, being the flap or portion on garment 210 (FIG. 2) from whichdevice 100 is hanging. Flipping the free end (top end 110) of device 100in this way allows an orientation of device 100 whereby the screen 130is facing more towards the body of the user and is right-side up (withtop end 110 away from the body and bottom end 120 close to the body) fornormal viewing by the user. Thus, the top end 110 can swing freely aboutits attachment point to the garment 210 while the bottom end 120 is heldclose to the body. When the person wearing the garment 210 and thedevice 100 sits down, there may be a natural tendency for the device 100to change orientation so that the display screen 130 become invertedenough (from its normal downwardly hanging position) to be readilyreadable by the person.

Stimulation device 100 may be configured so that when it is being wornin an orientation where top end 110 is held close to the user's body andbottom end 120 is swinging freely below top end 120, the display shownby screen 130 appears upside-down to an observer looking at the user.When stimulation device 100 is flipped up by the user about the pivot atthe bottom end 120, the display shown on screen 130 may appearright-side-up to the user as the user glances down at the device 100.

In some embodiments, screen 130 may be configured to change theorientation of the data it displays based on input from anaccelerometer, so that any text or images on screen 130 are the correctway up for reading or viewing regardless of the orientation ofstimulation device 100.

Stimulation device 100 may include an internal power source, such as abattery pack, allowing it to be portable. Stimulation device 100 mayfurther include a power input 150 to receive the connector of anexternal power source, which may be a plug pack to be plugged into amains power source. The external power source may be used as a way ofcharging the internal power supply. Stimulation device 100 may furtherinclude a USB port 140 for the receipt of a USB cable for communicationto external computing devices.

Stimulation device 100 may include input means such as buttons, a touchscreen, or switches. In some embodiments, stimulation device 100 has aminimal number of buttons, such as only 3, 4 or 5 buttons. This makesthe device relatively easy to use and less confusing for the user. Inthe illustrated embodiment, stimulation device 100 has power button 170,treatment level decrease button 180 and treatment level increase button185, as well as volume slide switch 190. This allows the user to powerthe device on and off, to adjust the level of stimulation administered,and to turn the volume of notifications and alarms on and off.

LCD segment display screen 130 provides a visual means of communicatingthe status of various settings of stimulation device 100 to the user.LCD segment display screen 130 may have between 60 and 90 segments, andin some embodiments may have in the order of 73 segments. Treatmentlevel display bar 132 shows the level of treatment being administered bythe device, with the amount of the bar illuminated indicating therelative strength of the stimulation pulses. Time remaining display 134is made up of several seven segment displays arranged to display a timein hours and minutes. These displays can also be configured to displayscrolling characters, which may be used to display messages to the user,such as when a treatment cycle has finished, or a greeting message whenthe device is powered on, for example. Sound indicator 135 may beilluminated when the sound is turned on by switch 190, and turned offwhen the sound is off. USB connection indicator 136 may be illuminatedwhen a USB connection is detected through USB port 140, and turned offwhen there is no USB connection. Battery indicator 137 may beilluminated when the battery power is sensed as being low, indicatingthat the device battery should be charged by connecting to a powersupply through power input 150. In some embodiments, a replaceablebattery may be used, and battery indicator 137 may be illuminated whenthe device battery should be replaced. The battery symbol may bedisplayed as full during the treatment stage. Pad fault indicator 138may be illuminated when stimulation device 100 senses that at least oneof the front and back electrode connector assemblies 220/230 isdisconnected from the device.

Device 100 may further include LEDs as an additional method of visualcommunication with the user. In the illustrated embodiment, LED 321 amay be a green LED used to illuminate power button 170 to indicate thatthe device is on. LED 321 b may be a yellow LED used to indicate thatthe device is administering treatment. In some embodiments LED 321 b maybe of a different colour, such as orange.

FIG. 2 shows a stimulation delivery and monitoring system 200 accordingto some embodiments. System 200 includes stimulation device 100, whichis electrically couplable to a back electrode connector assembly 220 anda front electrode connector assembly 230 by back and front electrodeconnection cables 222 and 232. Back and front electrode connector cables222 and 232 connect to device 100 through back and front cableconnectors 224 and 234, via connector inputs 165 and 160. In someembodiments, the stimulation generation device 100 is arranged totransmit electrical potential to the back and front electrode connectorassemblies 220 and 230 via the connector inputs 165 and 160 and the backand front cable connectors 224 and 234.

Back and front electrode connector assemblies 220 and 230 may beattachable to a garment to be worn by a patient being treated. In theillustrated embodiment, the garment may be a belt 210, consisting of aback belt portion 212 and a front belt portion 216, attachable to eachother by a temporary fastening means such as Velcro tape, allowing foran adjustment in size to match the body of the wearer. Back and frontelectrode connector assemblies 220 and 230 each have multiple electrodeconnectors 226 and 236. In some embodiments, each electrode connectorassembly may have two, four or six electrode connectors 226/236. Backand front electrode connectors 226 and 236 are removably couplable toback and front belt portions 212 and 216 by mating snap connector parts(not shown) coinciding with back and front belt electrode placement pads214 and 218.

Stimulation device 100 may be electrically couplable to an externalpower source, which may be an AC/DC plug pack 260 to plug into a mainspower supply. The external power source may be used to recharge anybatteries that are used to operate the device. AC/DC plug pack 260 maybe electrically coupled to stimulation device 100 by a cable pluggedinto power input 150 of the device. Stimulation device 100 may furtherbe electrically couplable to a computing device 240, which may be adesktop computer, laptop computer, tablet, smartphone, or other device.The coupling may be by connection with USB cable 250 between USB port140 on the stimulation device, and a USB port on computing device 240.This connection may allow for communication between stimulation device100 and computing device 240 via USB protocol, allowing for theadjustment of treatment settings, and the monitoring of the history oftreatment given by stimulation device 100.

In some embodiments, device 100 logs data and records treatment historyinto an on-chip memory which may later be accessible by computing device240. Such data may include information about a treatment session, suchas the treatment duration, the date the treatment was administered, thetime the treatment was administered and the intensity of the stimulationsignals delivered during treatment. Communication between stimulationdevice 100 and computing device 240 may alternatively be achievedthrough a wireless protocol, such as Bluetooth or Wi-Fi, or through analternative wired communication protocol. Alternatively, communicationbetween stimulation device 100 and computing device 240 may be effectedvia an intermediate device, such as a handheld computing device (like asmart phone). Furthermore, the communication may be achieved via atelecommunications network, or via the Internet.

FIG. 3 shows a block diagram of electronic circuitry 300 containedwithin housing 105 of some embodiments of the stimulation device 100.AC/DC plug pack 260 is electrically coupled to battery charger 325. Plugpack 260 may be in the range of 4.5 to 5.5V. Battery charger 325 chargesbattery 330, which may be by trickle charging or by high currentcharging. Battery charger 325 may be connected to battery 330 through acharge management controller within battery charger 325. Potentialvoltage ripple may be filtered by a capacitor, which may be in the orderof 10 μF in some embodiments. Battery charger 325 may be the LinearTechnologies LTC4001 in some embodiments.

Battery charger 325 provides charging data to battery monitor 335.Battery monitor 335 monitors the battery voltage through a voltagedivider, which may consist of two 150 kΩ resistors in some embodiments.The resultant voltage, equivalent to half of the battery voltage, isthen presented to an ADC port of microcontroller 355.

Battery charger 325 may have overvoltage and reverse polarity protectioncircuitry, which may allow charging between the ranges of 4.5 to 5.5V,but inhibit voltages above 6V and up to a practical working voltage of12V from reaching the charger. This may be implemented using anovervoltage protector such as the Linear LTC4360-2 or the LinearLTC4361-2.

Battery 330 supplies power supply unit 340, which may consist of twovoltage rails 345 and 350. Rail 345 may be a 3.3 VDC rail supplied froma low drop-out or a Buck/Boost regulator, and is used to supply thelogic and microcontroller 355. Rail 350 may be a 10 VDC rail or a 12 VDCrail in some embodiments, supplied from a boost regulator, and may beused to supply output stage 380. The boost converter may be configuredto supply any voltage between 10 VDC and 15 VDC. Device 100 may includepower plug protection to detect whether or not AC/DC plug pack 250 isconnected to battery charger 325. In some embodiments, this data may besent to microcontroller 355, which may disable the boost convertersupplying 10 VDC or 12 VDC rail 350 when AC/DC plug pack 250 isconnected, to disable electrode connectors 226 and 236 from deliveringstimulation pulses while device 100 is charging. In some otherembodiments, the stimulation pulses may be disabled in hardware throughan external power plug connection input.

Microcontroller 355 may be from the STM32F1 family of microcontrollers,and may include peripheral support for a UART for debugging purposes, aUSB controller, real time clock 360, at least 2 digital-to-analogueconverters (DACs), in the order of 2 to 6 analogue to digital converters(ADCs), and a serial peripheral interface for an LCD controller.Microcontroller 355 communicates with watchdog 365 to limit thelikelihood of a system failure caused by a runaway controller. Watchdog365 may perform functions including monitoring microcontroller 355,resetting microcontroller 355 if watchdog 365 is not serviced within anallowable time interval, latching a reset event to be visible tomicrocontroller 355 for logging reasons, and latching off output stage380 during a reset event to prevent device 100 from continuing todeliver stimulation pulses through electrode connectors 225 and 236until this is cleared by microcontroller 355. Watchdog 365 may be STMicroelectronics STWD100PY. This may be connected to hard resetcircuitry to allow for a reset of the device when required. In someembodiments, watchdog 365 may be a watchdog internal to microcontroller355.

Microcontroller 355 has access to memory (not shown) within the device100. The memory may include ROM, RAM, flash, or other memory types. Thememory may store instruction code, firmware image, configurationparameters and logged history data for device 100. Device 100 may makethe contents of the memory available to computing device 240 when device100 is connected to communicatively computing device 100, which might bethrough a physical connection with USB cable 250 in some embodiments.

A PC based application 310 may be run on a computing device 240 tocommunicate with device 100 through a USB interface. This communicationmay allow for a user using computing device 240 to set up settings ofdevice 10, such as the treatment durations and levels. Computing device240 may have USB interface 315, connectable through to USB port 140 ofthe device through a USB cable 250. USB port 140 is isolated frompatient contacting part 395 of device 100 through an isolation component385, which may be a 4 Kv I-coupler in some embodiments, such that theUSB interface is used for data exchange only. USB port may be requiredto be USB 2.0 compliant, and EMC compliant.

Microcontroller 355 may communicate to user interface components ofdevice 100 such as LEDs 321, buzzers 322 and vibration motor 323, an LCDdisplay 130 which may include backlight 390 and buttons 170, 180 and185. LEDs 321 may be used to illuminate power button 170 when the deviceis on. A buzzer 322 may be used to play alerts and alarms to the user toindicate the start and/or end of treatment cycles. The chassis of device100 may be designed to have an acoustic cavity to amplify the soundemitted from the buzzer 322. The buzzer 322 may be disabled by the userby switching volume slide switch 190. In addition or alternatively tothe buzzer 322, a vibration motor 323 may be used to alert the user byvibrating the device. This may be used in conjunction with the buzzer322, or may be turned on only when the device is in silent mode.

Microcontroller 355 controls the power supplied to output stage 380,driving this through its DACs. Output stage 380 may include circuitryconfigured to generate transcutaneous stimulation signals. Output stage380 may have two output channels, which may be a 4 kHz channel and a 4kHz plus 180 Hz channel. In some other embodiments, these may be a 4 kHzchannel, and a channel sweeping between 4080 and 4160 Hz. Filter 370 maybe used to achieve a flat frequency response in the pass band, which maybe in the order of 3800 Hz to 4200 Hz, centred around 4000 Hz. Filter370 may be a two stage, four pole filter, to provide a reasonably fastroll off with minimal component count. Output stage 380 receives inputfrom filter 370 and may drive output transformers. There may be onetransformer for each electrode connector 226 or 236. For example, wherethere are 4 electrodes, there may be 4 transformers. Where there are 4transformers, in some embodiments only 2 transformers may be active atany given time. Further functions and operation of a 4 transformerdesign are described below with reference to FIG. 34.

The secondary winding of the transformers may include short circuitprotection implemented by PTC (positive temperature coefficient)devices, other resettable fuses or resistors. These provide currentlimiting which reduce the impact of a short circuit condition. In someembodiments, the output current may be limited to 100 mA, for example.The operation of output stage 380 and the output transformers mayfurther limit the maximum output voltage in open circuit or under veryhigh impedance. In some embodiments, this may be limited to 500V, forexample. Furthermore, output stage 380 and the output transformers mayallow for other safety requirements to be met. For example, output stage380 may limit the maximum current delivered into a 1 KΩ load, which maybe limited to 55 mA peak-to-peak in some embodiments. In someembodiments, the hardware of the device provides safety features tolimit the harm to a patient that can be caused by the malfunction of thesoftware or firmware of the device.

Output stage 380 supplies data to feedback circuitry 375, whichcommunicates with microcontroller 355 to ensure the correct stimulationlevel is being delivered. Feedback circuitry 375 may allow for thedetection of connectivity of electrode connectors 226 or 236, and alertthe user and/or stop delivering stimulation signals when the electrodesbecome disconnected. This detection may be based in software, calculatedusing the magnitude of the generated sine wave by a DAC ofmicrocontroller 355 and a measured RMS primary current, in someembodiments.

The design of the device 100 and system 200 is such that patient safetyis assured by hardware. The firmware and software may also be configuredto provide additional levels of safety to the patient.

The device 100 may minimise power consumption in two ways: utilisingmodes of microcontroller 355, such as Stop and Sleep modes of STM32processor, whenever idle, and switching off peripheral devices wheneverthey are not in use. The microcontroller 355 may be put into Sleep modewhenever it is idle but its peripherals are in use (e.g. duringtreatment), to be woken via a facility such as the STM32Wait-For-Interrupt facility. A low-priority thread (the Sleep Managerdaemon) will when executed:

-   -   Disable the scheduler to prevent higher-priority threads from        executing until the SysTick service has been re-enabled;    -   Disable the SysTick service;    -   Enter a low-power mode.

It is necessary to use an application thread (the daemon) to handle thisrather than simply augment the system idle thread as RTX calls cannot bemade from the Idle thread. The microcontroller 355 exits Sleep mode oninterrupt from any of the following peripheral devices:

-   -   Real-Time Clock (RTC)—scheduled alarm;    -   External power applied/removed;    -   General Purpose Input Output (GPIO) Interrupt (for a button        press);    -   USB SOF present.

On exit from the appropriate interrupt service routine, the processor355 will resume normal execution. Servicing of the interrupt may haveleft a client thread in the runnable state, in which case it will bescheduled immediately; otherwise the Sleep Manager daemon thread will bescheduled (again). In the latter case, the microcontroller willimmediately re-enter Sleep mode.

When the main Command thread detects that there is no application workto do, the Device will enter an even lower power mode, “stop”. In thismode, as well as halting the CPU, the microcontroller 355 will stopclocking most internal peripherals. This state will be exited by one offour events:

-   -   RTC tick alarm (for servicing the watchdog)    -   Power button being pressed    -   External power being connected    -   USB receiving SOF indications.

Applications within the device 100 may be configured to ensure minimalpower consumption by only enabling those peripherals (internal andexternal) as and when required. Thus, by the time the command threadenters stop mode, most peripherals will already be switched offMicrocontroller 355 may have modes to preserve the contents of Ram. Forexample, the STM32 Power modes to be used, Stop and Sleep, both preservethe contents of RAM. In some embodiments, power usage may be minimisedby shutting down the core of microcontroller 355 when treatment is notbeing administered.

Device 100 may utilise the on chip real-time clock to provide a ticksource for executing the OS and associated timers. The real-time clockcan be set via the USB host communications interface either duringmanufacturing or by a clinician. A consequence of the processorsometimes entering Sleep mode is that the RTX SysTick interrupt will notoccur and all RTX-based timers will not accurately reflect real time.The firmware must employ timers to manage its real-time obligations,such as timeouts, so the on-chip Real-Time Clock (RTC) will be used asthe time source for all firmware operations.

The architecture of device 100 may employ concurrency to allow eachcommunications interface to be managed in relative isolation from therest of the firmware system. This may be handled by multithreading, withseparate threads to handle the various communications sources. In themajority of cases, each thread will have an ‘in-bound’ message queuethat other threads may use to communicate with it. The firmwarecomplexities often associated with thread synchronisation will behandled primarily by isolating all thread interactions to a small numberof utility classes, allowing the bulk of the code to be oblivious to themultithreaded environment.

Inter-Process Communication (IPC) mechanisms may be hidden behind thefirmware interface for a given component, and thus the chosen IPCimplementation may be free to change without affecting the abstractinterface between any two components, i.e. a client will not know that amessage queue is being used as the IPC mechanism. The architecture ofdevice 100 may generally decouple the firmware components to givemaximal flexibility with regard to how they are integrated together toform a working system. The firmware may be divided into layers oflogical dependency such that a firmware component will have acompile-time dependence only on other components that reside in the sameor lower layers of the architecture. There may also be a run-timedecoupling of physical dependency between major architecturalcomponents, based on dependency injection. For example, where object Arequires the services of object B, the service provided by object B willfrequently be abstracted behind an interface and object A will beinjected with an interface pointer (or reference) to the abstractservice. Thus construction of B will be hidden from A, which willpreserve A's flexibility to be provided with alternate implementationsof the service. In keeping with this theme, use of the Singleton patternwill be kept to a minimum and where possible the location of such globalresources will be injected into their clients, thus avoiding the need tosearch for them. This approach will allow a variety of differentexecutable images to be built, with minimal code differences betweenfirmware components common to different executable images. This shouldfacilitate unit testing of individual components through stubbing ofother components.

The firmware may be upgraded in the field, via the USB hostcommunications interface. For this purpose, the architecture:

-   -   Ensures that there is sufficient memory to enable a second code        image to be held temporarily    -   Ensures that the Flash memory can be reprogrammed by the Device        firmware itself.

A new firmware image for the microcontroller 355 can be downloaded overUSB and stored in a special area of the internal flash. The firmwarewill be restarted and the bootloader will detect the upgrade image inthe secondary area, and re-program the primary internal flash ofmicrocontroller 355 with the new firmware. On completion, the firmwarewill be restarted to boot the new firmware version. Should the transferof firmware image from external to internal flash be interrupted, thebootloader will re-attempt the re-programming at the next power-up. Thedevice 100 memory map identifies the storage and/or execution regionsfor the microcontroller 355 firmware. The upgrade facility may operateon a “complete” upgrade package, replacing the entire existing imagewith a new complete image.

External host communications are programmed to support:

-   -   Firmware upgrade;    -   Clinical configuration of treatment parameters;    -   Test result record transfer, including patient test results and        fault log.

The firmware may operate based on a simple event handling model whereeach thread will wait on a set of event flags for an event to besignalled. The event sources can be internal as a result of IPC, i.e. amessage being posted to a threads input queue or an external event wherea device has asserted some condition of interest. In the latter case,the condition is detected by the associated device driver and translatedinto an internal event and dispatched to the appropriate thread. Takingthe case of a device interrupt, the driver will handle the interrupt(satisfying the devices requirements) and shall then signal a client bysetting the event flag supplied by the client at run-time. A similarmechanism is used when a driver is requested to complete an operationfor which the client thread does not wish to block. Instead it requeststhat the driver set the specified event flag when the asynchronousoperation is complete.

The event management mechanism is structured such that each thread canwait on up to sixteen separate events flags, thus at least sixteenseparate events (although some events could be signalled by acombination of events). A priority scheme has allocated each firmwarethread based on the frequency of key input events.

As an example, the device 100 hardware may provide the following memoryresources:

-   -   96 KB on-chip RAM;    -   768 KB on-chip Flash.

In some embodiments, no external memory will be present, so the firmwaredesign may be constrained to fit within the internally availableresources. A ‘two-region model’ may be used for heap and stack and theon-chip RAM may be divided between these two regions:

-   -   the allocation of ‘system objects’ (threads, stacks, semaphores,        etc.) that have a persistence roughly equal to the run-time of        the product, i.e. they are created at power-up and never        destroyed by the firmware;    -   A small amount of RAM will be used for statically-allocated        data, primarily as required by the compiler and run-time        library. During bootstrap, space will be reserved for the        statically-allocated data (identified by the linker as        read-only, zero-initialised or general read-write data). Driver        objects and their associated buffers will be created in on-chip        RAM from a special memory pool.

The on-chip RAM may also be used for:

-   -   The per-thread call stacks;    -   The system heap from which dynamic allocations will take place        (for non-system objects).

While dynamic allocation cannot be eradicated from the firmware, it isrequired where possible that allocations be made once at initialisationtime and never de-allocated. By moving to this more static model, it isexpected that the memory utilisation will be easier to monitor andcontrol, providing the essential data for any subsequent optimisationsto take place.

The on-chip flash memory may be used for the storage and in-placeexecution of the bootloader and the main application program code. Theflash may be accessed ‘raw’ with no real file system in place. Whileproviding ease of development, a full blown file system would consumeconsiderable resource and also prevent efficient use of the underlyingflash memory. As such, wear-levelling must be considered and factoredinto the design of individual components which require flash access.Essentially three types of data/style of access may be used:

-   -   Program code: changing infrequently/wear-levelling not a        concern;    -   Clinical settings: changing at low frequency/wear-levelling not        a concern—as these are only changed by a clinician or health        care practitioner, they are unlikely to be changed more than        once a month or 36 times over the product lifetime;    -   Patient Test Results: changing at higher        frequency/wear-levelling still not a concern—the Device        allocates space for 180 treatment records, which are all erased        by a clinician and subsequently filled up at the rate of once        per treatment.    -   In all cases, the maximum number of erase/write cycles for each        area is expected to be less than 100 over the lifetime of the        product. Therefore, no wear-levelling is required.    -   To allow concurrent write/erase operations on data areas and        program execution, a two-bank microcontroller is specified. The        code image being executed is located in the second back,        allowing slow operations (write and erase) to block accesses to        the other bank without affecting normal driver operation.        Components using the Flash which might be blocked by such data        operations may be designed to avoid being blocked at        inconvenient times.

FIG. 4 shows a block diagram of firmware 400 of stimulation device 100.Firmware 400 runs on microcontroller 355 atop an operating system, whichin some embodiments may be a real-time operating system (RTOS) such asthe Keil RTX RTOS. Configuration component 410 is responsible fordetermining the application firmware configuration to be executed,comprising the concrete objects instantiated behind key abstractinterfaces as well as the threads to be run. The key abstract interfacesmay relate to initialisation for a specific target operating system, theselection of drivers to be started and their specific implementations,and concrete instances of OS Abstraction components. Configurationcomponent 410 has compile-time dependencies across the entire set offirmware components and allows many firmware components to be isolatedfrom other firmware components by using a dependency injection designpattern to manipulate the dependencies.

At the application level, application threads 420 provide the core logicof the firmware and manage the therapy, power management, user interfaceand host communications. Command thread 421 provides the finite statemachine model for the behaviour of device 100 and manages, from a highlevel, all interactions with peripheral devices. Battery manager thread422 monitors the voltage level of battery 330 and the presence of apower source connected to battery charger 325, and runs the chargingprocess. Host communications thread 423 handles communications with theexternal USB-connected host, which may be computing device 240, andprovides a context for the protocol layers to function. Sleep managerthread 424 temporarily suspends microcontroller 355 when there is nowork to do. Treatment manager thread 425 is a top-level thread foroverall control of a treatment cycle. UI Manager thread 426 isresponsible for all user interface input and output, including buttons170, 180 and 185, LEDs 321, buzzers 322 and vibration motor 323, and LCD130. Watchdog manager thread 427 is responsible for ensuring that othersystem components are working correctly and servicing the watchdog 365at suitable intervals.

Worker components 430 are a group of components that perform thefunctions of the device 100, executing in the context of one (or more)of the application threads 420. Alert manager component 431 controls thenon-visual output devices, which may include the buzzer 322 and thevibrator motor 323 in some embodiments. Battery monitor component 432monitors the level of charge in battery 330. Button monitor components433 make up part of UI manager thread 426, and each instance monitors asingle button 170, 180 or 185, debouncing, classifying and signalling tothe button manager component 434. Button manager component 434 overseesthe multiple button monitor components 433, extracting the key eventsfor each button 170, 180 and 185, detecting button combinations andreporting events to other system components. Charging manager component435 control and monitor the battery charging process. Configurationmanager component 436 orchestrates the final configuration process.Display manager component 437 controls the visual output devices, whichin some embodiments may include LEDs 321 and the segmented LCD 130. LEDs321 may be controlled directly, while LCD 130 may be controlledindirectly via LCD driver component 438. LCD driver component 438generates sequences of I2C messages to configure the LCD display 130 andto then enable/disable the entire display and individual segments.Output monitor component 439 tracks the transcutaneous interferentialcurrent stimulation therapy being provided to the patient and identifiespad connection faults. Parameter manager component 440 controls accessto and integrity of system parameters. Power manager component 441 putsdevice 100 into the lowest possible power mode when it is between uses.The working components may include a watchdog controller component 442to provide access to external watchdog 365 to protect key executionareas. In some other embodiments, an internal watchdog may be used.Waveform manager component 443 is part of the treatment process thatuses waveform buffer components 444 to control the frequency andstrength of the generated waveforms. Waveform buffer components 444 areused by waveform manager component 443 to create and hold the digitalrepresentation of a sine wave.

Firmware drivers 450 all share a common abstract interface defined bythe OS abstraction component 470 and have individual derived (abstract)classes specific to their function, as well as further derived classesfor the platform-specific implementation. This organisation allows someoperations to be performed on all drivers 450 (e.g. during systeminitialisation) and device-specific operations to be performed ondrivers 450 by client threads that are oblivious to the specificoperating system and hardware platform. Each driver 450 will provide anapplication program interface (API) that executes within the context ofone or more client threads, as well as an Interrupt Service Routine(ISR) if required for the specific peripheral and shared data structuresfor communication between the ISR and the client thread. One or moreinstances of each driver class will be created as required. Clientcomponents will be injected by configuration component 410 with thedriver objects they require.

ADC driver component 451 configures and reads the on-chip ADCperipheral. DAC driver component 452 configures and writes the on-chipDAC peripheral. DMAC driver component 453 configures and controls theDirect Memory Access Controllers. Flash driver component 454 reads,writes and erases functions for internal flash. GPIO driver component455 controls the reading, writing and interrupt reporting for GeneralPurpose Input Output (GPIO) signals. I2C driver component 456 writesconfiguration and control messages to the segmented LCD 130. PWM drivercomponent 457 produces pulse-width modulated output on selected GPIOlines. Reset driver component 458 handles microcontroller 355 resetfunctions and the on-chip watchdog. RTC driver component 459 accesseson-chip real-time clock 360. Serial driver component 460 handlesasynchronous communications via UART devices. Timer driver component 461configures and manages the underlying timer implementation. USB coredriver component 462 and USB HID driver component 463 give access to theUSB peripheral.

Higher-layer components may reside atop these platform-specific driversto bridge between application components and drivers.

Logging component 460 supports development by allowing configurablegeneration of execution trace messages which are output to a ‘loggingdevice’, i.e. a serial port or a flash device. The firmware is dividedinto notional logging domains with each being assigned a loggingthreshold at start-up. The firmware executing within a logging domaincan generate a log message at a specific level if that level exceeds thethreshold configured for that domain. This allows for logging output tobe generated at varying levels of detail to support debugging. In someembodiments logging may be able to be disabled, to reduce the run-timeand code-space overheads where this may be particularly required.

Bootloader component 465 is responsible for initialising the platform.This may include establishing a run-time environment, completing anypending firmware upgrade operations, and verifying and booting theinstalled application. Bootloader component 465 keeps peripherals notrequired prior to application start-up in a low-power mode, i.e. reset,not clocked or off.

In some embodiments, firmware 400 may include Keil RL-ARM component 455,which may be a 3rd-party library that contains several middlewarecomponents. In some embodiments, the middleware components may includethe RTX operating system. In some embodiments, firmware 400 may includealternative libraries and/or other middleware components.

OS abstraction component 470 provides abstract interfaces which isolatemost of the firmware from the actual operating system and its underlyinghardware. OS abstraction component 470 also includes implementations ofthose interfaces for target operating system 490, which may be Windowsor RTX in some embodiments, and for the hardware platforms, which mayinclude desktop PCs, STM32 platforms including evaluation boards,prototype TBCTD hardware and final TBCTD hardware.

In some embodiments, firmware 400 includes ST firmware library 480,being a Keil RTX-compatible ST Micro firmware library. Some embodimentsmay use alternative libraries compatible with other operating systems.

Target operating system 490 may be a 3rd-party Keil RTX Real-TimeOperating System (RTOS) or Windows, or another operating system.

FIG. 5 is a block diagram of the application threads and inter-processcommunication 500 of firmware 400 of device 100. Firmware may include aconfiguration thread (not shown). The configuration thread may be aninitial thread launched by target operating system 490, and may serve tocreate all the necessary system resources and launch the applicationthreads. Once the other threads have been started it may no longer berequired and may be terminated by command thread 421. It is vital thatthis thread run at a priority higher than all others to ensure that itcompletes its execution before any other application thread is scheduledto run.

Command thread 421 provides a central control of device 100 and isstimulated by events being posted on its input queue and from timerscreated and maintained internal to the thread. Its primary tasks are:maintaining the system state; noting signals requesting or requiringstate changes (e.g. charger being connected), selecting thehighest-priority function to be run; stopping and starting applications;stopping the microcontroller to conserve power when the system iscompletely idle. Command thread 421 may receive messages and eventstatus updates from a number of sources. For example, it may receivemessages from battery manager thread 422 to communicate that theexternal charger is disconnected, or when charging is complete. It mayreceive messages from host communications thread 423 when the hostcommunications become active or inactive, or when the firmware image isbeing updated. Treatment manager thread 425 may send messages to commandthread 421 when a pad fault is detected, or when the pad status changes.Command thread 421 may also receive messages from user interface managerthread 426 to notify it of user input events (such as buttons 170, 180or 185 being pressed) or of when output operations are complete. Commandthread 421 may also receive asynchronous notifications, of events suchas USB activity, activation of the power button, when AC/DC plug pack260 is connected, timer ticks, and when the watchdog requires service.

Battery manager thread 422 may provide a number of services to device100. These may include monitoring the voltage of the battery for thepurpose of generating and reporting battery level/status alerts toclients, monitoring the connection and disconnection of the externalpower supply, and controlling the charging process. Battery managerthread 422 may receive a number of messages from other threads. Forexample, it may receive “start charging” or “stop charging” commandsfrom command thread 421. It may also receive asynchronous notifications,of events such as when conversion is completed by an ADC, and of timerticks. Battery manager thread 422 may be configured with settings toallow the battery 330 to maintain sufficient charge for up to 6 monthsto keep data, such as stimulation delivery data, in the device memory(not shown), in some embodiments. The battery 330 may be partitioned sothat it does not go completely flat and can therefore maintain the clockand date functions in the data storage. In some other embodiments, thebattery may be connected to microcontroller 355 via a voltage divider,to allow the core of microcontroller 355 to be shut down whenevertreatment is not being administered, so that only the clock, date anddata storage functions are maintained.

Host communication thread 423 handles all communications between device100 and the external computing device 240 via the USB link 250. Hostcommunication thread 423 may receive messages from command thread 421when an operation succeeded or failed. Host communication thread 423 mayalso receive asynchronous notifications due to interrupt driven events,such as notifications from of USB activity, USB idleness, and whethermessages were received via USB.

Sleep Manager thread 424 is the lowest priority thread in the system andexecutes when there is no higher-priority application work to be done,putting microcontroller 355 into its Sleep mode. This priority structureresults in an automatic shutdown of device 100's CPU (but not itsperipherals) into a low-power mode when there is no outstandingapplication work to be done. This thread essentially halts the systemusing the wait-for-interrupt command and thus the last instruction toget executed upon entry to the low-power mode will be within the contextof this thread and likewise be the first instruction executed at exitfrom the low-power mode.

An even lower power mode, Stopped, may be used when the Device iscompletely idle; this stops the CPU and internal peripherals as well aspowering-down external circuitry. These two schemes are complementary:one saving power during operations, the other saving power betweenoperations.

Treatment manager thread 425 is the top-level thread for providingtreatment, being the provision of stimulation signals to electrodeconnectors 226 and 236. Primarily, this thread decides when treatmentstarts and ends, and the parameters for the treatment; it then instructsother components to perform various aspects of the treatment process(generating frequencies at specific levels to specific pads); it alsoreports progress to the UI and records treatment record to Flash. Italso implements the final treatment start level configuration stage,where a new patient selects a desired start treatment level. Treatmentmanager thread 425 may monitor the therapy being received by the patientto detect pad connection faults. If a fault is detected, treatment maybe suspended and the patient may be alerted. Treatment manager thread425 may receive messages from command thread 421 telling it to stop orstart treatment, or informing it of user input events, such as buttonpresses. Treatment manager thread 425 may further receive asynchronousnotifications due to interrupt driven events. For example, some of theseevents may include completion of conversion or errors during conversionby DACs or ADCs, and notifications from the timer service based on dutycycle service timers, direction change timers, frequency change timers,output check timers and level change timers.

User interface manager thread 426 may comprise two main strands, beingthe UI manager and the display manager. The UI manager may be atop-level component, interfacing between all the UI threads and othermodules, and performing some sequencing operations within the UI module.The display manager may run the visual UI. Inputs may come from varioussources, and a number of output devices are under user interface managerthread 426's control. For example, UI manager thread 426 may display theelements and data requested in the specified formats; sequenceanimations if required; and drive the LCD power and backlight inaccordance with the user settings, user interaction and as requested bythe command thread 421. UI manager thread 426 may receive a number ofmessages from command thread 421, including requests to signal aspecified treatment level, a specified reference level, a pad faultpattern (or no fault), a time period, a warning, power, battery level, alow battery condition, that treatment is complete, an error condition, akey-click, an at-limit condition, the introductory message, or that thedefault level has been set. It may also receive requests to enable LCD130, to disable LCD 130, to enable LCD's backlight 390, to display aspecified format, or to display a specified string of text. It may alsoreceive messages and notifications from the UI alert manager and UIbutton manager threads.

The UI alert manager is a thread within the UI module. It runs thenon-visual UI outputs, namely the audible buzzer 322 and the vibrator323. It may be responsible for functions such as generating the requiredsequences; using the “mute” switch position to decide if audible outputis required; and driving the two output devices.

The UI button manager thread is another thread within the UI module. Itmonitors the push buttons operated by the user, which are connected toGPIO (input) pins on the microcontroller 355. These inputs arede-bounced and gated, and then trigger event messages to other threads.

The UI LCD driver thread is a further thread within the UI module. It isresponsible for sending configuration commands via the I2C driver, whichmay be sent at start-up, to configure the device for use; during deviceoperations, to turn the display on and off; and during device operation,to turn individual segments on and off.

Watchdog manager thread 427 manages the on-chip watchdog by resetting itwhen commanded to do so. The thread simply blocks on a semaphore andthis semaphore is posted by a client thread when it is time to servicethe watchdog. The watchdog strategy requires that this thread have apriority of one higher than sleep management thread 424 and thecommanding thread be of a significantly higher priority in the processset and also be a thread that runs frequently. In some embodiments,command thread 421 may be the commanding thread. The resultant prioritystructure sees a high priority thread being required to run to activatethe watchdog thread which itself is low priority and thus if thewatchdog is being correctly maintained then one can be reasonablyconfident that neither deadlock nor priority inversion is taking place(for a significant period of time).

Logging thread 550 collects log messages on behalf of the other threadsand writes to logging port 560 to output the log messages. Theunderlying device could log to a serial port or to flash forexample—logging thread 550 is not concerned with the underlyingimplementation of logging port 560.

Competing with the application threads is the firmware executing withinthe various Interrupt Service Routines (ISR). Nested (parallel)interrupt handling may be used to ensure that the most time-criticalinterrupts are serviced in a timely manner.

FIG. 6 shows a state diagram illustrating the system states 600 ofdevice 100. Device 100 may be configured such that firmware 400 operatesin one of four mutually-exclusive modes, implemented by command thread421. In some embodiments, these may be host connected mode 610, chargingmode 620, treatment mode 630 and idle mode 640. In host connected mode610, device 100 may be inoperable to the user and may be under thecontrol of a host application run on USB-connected computing device 240for the purpose of retrieving test results, device information andconfiguration data from device 100; updating configuration data storedon the device 100; and transferring a new firmware image to device 100.In charging mode 620 device 100 may be connected to AC/DC plug pack 260.In treatment mode 630, device 100 may be supplying electricalstimulation signals to electrode connectors 226 and 236 in order toprovide transcutaneous stimulation to a patient by way of treatment. Inidle mode 640, device 100 may not be performing any tasks. In someembodiments, this mode may consist of two internal modes, being waitingmode 642 and stopped mode 644, which device 100 may transition betweenbased on an interrupt event. Device 100 also enters power-up mode 650when powered up or reset.

FIG. 7 is a flow chart diagram illustrating method 700 of usingstimulation device 100. The device is powered up at step 710. In someembodiments, this may be done by holding power button 170 for a setduration of time. In some embodiments, this duration may be in the orderof 3 seconds, for example. The device then moves to an introductorydisplay at step 720. This may give the user visual, aural and/or tactileindication that the device has been powered on. For example, the buzzer322 may be caused to emit a beeping noise, which may continue for aduration of around 1 second in some embodiments. Vibration motor 323 maybe activated to cause the device to vibrate briefly. Furthermore oralternatively, the device may be caused to display a message. Forexample, the word “Hello” may be caused to be displayed and cycled onLCD 130 for a duration of around 4 seconds. LEDs 321 may illuminate. Insome embodiments, LED 321 a and LED 321 b may illuminate, indicatingthat the device is powered on and that treatment is starting,respectively.

If a pad fault is detected by output monitor component 439, device 100moves to step 725. Device 100 produces signals to indicate to the userthat a fault has occurred. For example, pad fault indicator 138 may beilluminated, buzzer 322 may beep 3 times, and vibration motor 323 maycause a brief vibration. Treatment level display bar 132 and timeremaining display 134 are turned off. These indicators prompt the userto troubleshoot, which may be by checking the connections and ensuringcable connectors 234 and 224 are properly plugged into connector inputs160 and 165. Once the fault is rectified, device 100 progressed to step730. If no pad fault was detected, device 100 moves directly from step720 to 730.

At 730, treatment mode commences. This may be a normal treatment mode ora safety treatment or control lock mode, as set up using computingdevice 240 prior to the use of the device. In treatment mode, device 100supplies stimulation signals to electrode connectors 226 and 236.Treatment level display bar 132 and time remaining display 134 areilluminating, showing a current treatment level, and the time remainingof the treatment period. The treatment level is the level of the currentof the stimulation signals being delivered via electrode connectors 226and 236. If the user presses any button, treatment ramp is cancelled at735. Treatment level does not ramp up, but treatment continues at thecurrent level. If the user does not press any buttons, device 100progresses to step 740, and the treatment level steadily ramps up to amaximum level as set prior to use through computing device 240. In someembodiments, this ramp up may take a period of around 20 seconds, forexample. Time remaining display 134 commences counting down the time oftreatment remaining. In some embodiments, an initial treatment time of 1hour may be set, and display 134 may count down each minute until 0minutes are remaining.

If a pad fault is detected by output monitor component 439, device 100moves to step 745. Device 100 produces signals to indicate to the userthat a fault has occurred. For example, pad fault indicator 138 may beilluminated, buzzer 322 may beep 3 times, and vibration motor 323 maycause a brief vibration. Treatment level display bar 132 and timeremaining display 134 are turned off. These indicators prompt the userto troubleshoot, which may be by checking the connections and ensuringcable connectors 234 and 224 are properly plugged into connector inputs160 and 165. Once the fault is rectified, device 100 may progress tostep 750. If no pad fault was detected, device 100 may move directlyfrom step 740 to 750.

If the user presses the treatment level decrease button 180 or thetreatment level increase button 185 from either step 735 or 740, device100 enters step 755 and the treatment level is adjusted up or downdepending on the button pressed. In some embodiments, the treatmentlevel is adjusted by 1 level increment each time one of the buttons 180or 185 are pressed. Some embodiments may have around 40 levels, with amaximum current of around 30 mA into a 1 kΩ load. Each level incrementcorresponds to about 0.75 or 1 mA for a body having 1 kΩ impedance, sowhile the change in stimulation intensity is intended to be about 0.75or 1 mA for each level, it will in practice vary from that amount,depending on the patient receiving the stimulation. In some embodiments,where the device is in a control lock mode (which may be termed a safetymode), the treatment level may increase or decrease a maximum of threelevels from the start level (i.e. resulting in a maximum intensityvariation from the start level of around 2 mA to 3 mA). Each time abutton 180 or 185 is pressed, the user may receive feedback that thebutton press was registered by device 100. For example, treatment leveldisplay bar 132 may display the new treatment level, and time remainingdisplay 134 may be used to display a numeric treatment level for aperiod, which may be in the order of 2 seconds in some embodiments.Where device 100 is in safety mode or control lock mode, device 100 maygive the user a visual, aural or tactile indication of when the maximumtreatment level has been reached. For example, buzzer 322 may emit ashort beep, and vibration motor 323 may cause device 100 to vibratebriefly. After a period of no buttons being pressed, which may be aperiod of 5 seconds, for example, device 100 moves from step 755 to 750.Alternatively, if the user holds power button 170 for a period, whichmay be a period of 3 seconds in some embodiments, device 100 may move tostep 780 and power off.

From step 750, the treatment continues at the level reached during rampup or set by the user, and the treatment time continues to count down.At step 760, when the treatment time is nearing to 0, such as when itreaches 1 minute, battery indicator 137 may flash to remind the user tocharge the device. When the countdown reaches 0, at step 770, treatmentends. This may be indicated to the user in a number of ways. Forexample, buzzer 322 may emit 1 long beep, corresponding to vibrationmotor 323 vibrating for one long period. In some other embodiments,buzzer 322 may emit 2 short beeps and 1 long beep, corresponding tovibration motor 323 vibrating for 2 short periods followed by one longerperiod. Time remaining display 134 may be used to display a message tothe user, which may be the word “End” in some embodiments. The devicemay stay switched on for a period of time, which may be 3 minutes insome embodiments, before automatically switching off. Alternatively, theuser may be able to power off the device by holding power button 170 fora period of time, such as a period of 3 seconds, for example.

FIG. 8 is a sequence diagram of a power-up initialisation sequence 800for device firmware 400. This sequence may be run when device firmware400 is initialised. As device 100 is normally powered by its internalrechargeable battery 330 (even when it appears to be “switched off”),this sequence seldom takes place. It may occurs when either power isfirst applied to device 100 during manufacturing, external power isconnected after battery 330 has run flat, firmware 400 is recoveringfollowing a serious failure (e.g. watchdog expiry); or firmware 400 isrestarted on command (e.g. after loading a new firmware image).

FIG. 9 is a sequence diagram of the host communication mode sequence 900for device firmware 400. Host communications mode 900 may be used byclinicians to set the operating parameters for subsequent treatments.Host communications mode 900 may be entered by connecting device 100 tocomputing device 240 using USB cable 250. As soon as the communicationslink becomes active, device 100 will wake-up or stop its currentactivity and enter host communications mode 900.

FIGS. 10a and 10b are sequence diagrams of the set device configurationsequences 1000 and 1050 for device firmware 400. Computing device 240may write the entire configuration in a single transaction. Device 100may accept this configuration as shown in FIG. 10a , or reject thisconfiguration in its entirety as shown in FIG. 10 b.

FIG. 11 is a sequence diagram of the read device configuration sequence1100 for device firmware 400. Computing device 240 reads allconfiguration information from device 100 in a single transaction. Insome embodiments, the active parameter values are held in RAM, so noFlash accesses are needed.

FIG. 12 is a sequence diagram of the clear treatment records sequence1200 for device firmware 400. Computing device 240 may have a singlecommand to erase all treatment records. In some embodiments, partialerasure may not be supported.

FIG. 13 is a sequence diagram of the treatment reporting sequence 1300for device firmware 400. Treatment reports may be built up within device100 during treatment and may be over-written when memory runs out, orthey may be deleted on command. A clinician may be able to read thetreatment reports from device 100 using computing device 240 via the USBcommunications interface.

FIG. 14 is a sequence diagram of the firmware upgrade sequence 1400 fordevice firmware 400. Device 100 may allow computing device 240 to sendit a new firmware image.

FIG. 15 is a sequence diagram of the charging sequence 1500 for devicefirmware 400. When the user connects an AC/DC plug pack 260 to device100 while it is not doing anything, device 100 may wake-up and startcharging.

FIG. 16 is a sequence diagram of the charging in host communicationsmode sequence 1600 for device firmware 400. If AC/DC plug pack 260 isconnected during host communications, host communications may beterminated.

FIG. 17 is a sequence diagram of the charging during treatment sequence1700 for device firmware 400. If charging is started during treatment,treatment stops. When charging completes, device 100 becomes idle; itdoes not automatically restart the interrupted treatment cycle.

FIG. 18 is a sequence diagram of the treatment while charging sequence1800 for device firmware 400. If device 100 is busy charging when theuser presses power button 170, device 100 will continue with its currentoperation. The only change the user will observe is that LCD display 130will illuminate for a period of time.

FIG. 19 is a sequence diagram of the treatment during hostcommunications sequence 1900 for device firmware 400. If device 100 isbusy talking to computing device 240 when the user presses power button170, device 100 will continue with its current operation. The onlychange the user will observe is that LCD display 130 will illuminate fora period of time.

FIG. 20 is a sequence diagram of the low battery sequence 2000 fordevice firmware 400. If the user switches device 100 on while battery330 has a low charge level, LCD display 130 will show a low batterywarning message for a period of time and then turn off.

FIG. 21 is a sequence diagram of the final configuration sequence 2100for device firmware 400. The final part of configuration is to tune thedefault power level to suit the patient. If this hasn't been done by theclinician, it will occur when device 100 is switched on by the user (inthe presence of a nurse). When device 100 is switched on by the user,device 100 checks if final configuration is required; if so, device 100enters a final configuration state. In this state, continuousstimulation is provided to the patient, starting at minimum power level.The user can increase or decrease this value (within clinician setlimits) using treatment level decrease button 180 and treatment levelincrease button 185 until the preferred level is found. The user thenpresses and holds both the treatment level decrease button 180 andtreatment level increase button 185 for a few seconds to signifyselection has been made. The default power level will then be saved, a“Set” message will be displayed on LCD 130 for a period of time and thenLCD 130 will switch off.

FIG. 22 is a sequence diagram of the treatment cycle sequence 2200 fordevice firmware 400. A treatment cycle is started by the user pressingpower button 170 while device 100 is switched on, or pressing powerbutton 170 twice when device 100 is in idle mode 640. A treatment cyclemay only take place if a series of pre-conditions are met. Some of thesepre-conditions may include: having sufficient power to complete thetreatment cycle; having either enough time passed after the last cycleor some treatment remaining from the last cycle; and the pads beingcorrectly positioned and connected to device 100.

FIG. 23 is a sequence diagram of the pad fault detection sequence 2300for device firmware 400. While therapy is being delivered (both actualtreatment and final configuration), device 100 continuously monitors theoutput feedback signals to ensure there are no pad connection issues. Ifthere are, the user is alerted and treatment is provided at minimumlevel (to allow pad testing) until proper connections are established. Apad fault may be detected by monitoring an RMS voltage based on thecurrent on the primary side of the output transformers. When themeasured voltage comes into a pre-determined range indicating that theimpedance at the electrodes is near open-circuit (this may be around 2kΩ, for example), a pad fault is detected. The pre-determined voltagerange may be configured through firmware, and may vary depending on thetreatment level being administered.

FIG. 24 is a sequence diagram of the adjustment during treatmentsequence 2400 for device firmware 400. During a treatment cycle, thepatient can adjust the intensity of treatment, within clinician setlimits, using treatment level decrease button 180 and treatment levelincrease button 185; intensity is increased or decreased by one quantumeach time one of these two buttons is released. If the appropriate limitis reached, further button operations in that direction are ignored.

FIG. 25 is a sequence diagram of the interrupted treatment sequence 2500for device firmware 400. The patient can suspend a therapy session byturning device 100 off mid cycle; this may be achieved by holding powerbutton 170 for a long period of time, which may be a period in the orderof 3 seconds in some embodiments. This may cause device 100 toimmediately power off. In some embodiments this does not trigger anyalert for the patient, as patient request initiated the event.Interrupted treatments are either abandoned by firmware 400 after aperiod of time, which may be in the order of 12 hours from the originalstart of treatment in some embodiments, or are continued by the patientrequesting a treatment cycle. Device 100 may be configured such that theinitial “time remaining” display shows the remaining time instead of thewhole treatment period.

FIG. 26 is a sequence diagram of the end of treatment indicationsequence 2600 for device firmware 400. At the end of a treatment cycle,therapy ceases, a report of any treatment which has accumulated in RAMmay be written to Flash, LCD display 130 may change to announce the endof cycle, and the vibrator 323 and (optionally) buzzer 322 may be usedto alert the user. Device 100 may then power down.

FIG. 27 is a sequence diagram of the scrolling text message sequence2700 for device firmware 400. This sequence is used to display textmessaged on LCD 130.

FIG. 28 is a sequence diagram of the device fault sequence 2800 fordevice firmware 400. If device 100 detects a hardware or firmwarefailure, it may display an error message on LCD 130 and then may appearto switch itself off. To maximise the chances of recovering from theerror, a system reset may be performed.

FIG. 29 is an example client-side display 2900 of a page of anapplication run on computing device 240. The application may allowsettings on device 100 to be adjusted and for monitoring of treatment tooccur. In some embodiments, the application may be able to assess device100 settings and data logs when computing device 240 is communicativelyconnected to device 100 with a USB connection. Display 2900 has patientdata tab 2910, treatment settings tab 2912 and device setup tab 2914.FIG. 29 shows patient data tab 2910 being open. Patient data tab 2910allows the user to view patient data using calendar view or an intensityview, by selecting buttons 2920 or 2922, respectively. FIG. 29 showscalendar view 2920 selected, as indicated by the illumination aroundthis button.

Selecting calendar view 2910 displays a monthly calendar 2930 made up ofdays 2940, with each day corresponding to a calendar year of a selectedmonth as shown on label 2960. The selected month may be automaticallyloaded to the current month when the application loads, or may bechanged by the user by scrolling through the months using buttons 2962and 2964. The calendar 2930 may display logging details of a device thathas already been used to administer treatment. Each day 2940 displaysthe date 2950 as well as the recorded amount of treatment that wasdelivered on that date. Each day further has indicator 2954, which theclinician can use to indicate the occurrence or non-occurrence of anevent (i.e. bowl movement), as reported by the patient. Each of thetreatment days in the calendar 2930 may include an indicator 2956 of atreatment proportion to indicate the relative duration of the treatmentadministered on the relevant day, compared to the scheduled, prescribedor intended treatment for that day. For example, if the treatment for agiven day was actually only delivered for 15 minutes instead of aspecified single 30 minute delivery period for that day, then thetreatment proportion indicator 2956 would show that only half (50%) ofthe treatment was delivered in that day.

Display 2900 may further have panels of information about the treatmenthistory. In the illustrated embodiment, display 2900 has start levelpanel 2970, average intensity panel 2972, average session panel 2974 andtreatment days panel 2976. Start level panel 2970 may show the defaultintensity level which the stimulation delivered by device 100 ramps upto during treatment. In some embodiments, the maximum treatment levelmay also be shown. In the illustrated embodiment, the start level isshown to be level 19, out of a maximum of 40 treatment levels. Averageintensity panel 2972 may show the average intensity of the stimulationsignals delivered over the monitored treatment period. The panel mayfurther show the maximum and minimum intensity levels delivered, as arange. In the illustrated embodiment, the average intensity is shown tobe 20, with a range of between 17 and 24. Average session panel 2974 mayshow the average duration for which stimulation signals were deliveredduring each day of treatment. It may also show the maximum treatmenttime available. In the illustrated embodiment, an average session timeof 45 minutes is shown, with the maximum treatment time being 60minutes. Treatment days panel 1976 may show the number of days duringthe treatment period on which stimulation signals were actuallyadministered, as well as the total number of days in the treatmentperiod. In the illustrated embodiment, the number of treatment days isshown to be 42, out of a treatment period of 45 days.

Display 2900 may have a refresh button 2982 to allow the user to refreshthe page, and an export button 2984 to allow the user to export theinformation to save to file or send to an email address. In someembodiments, display 2900 may further have a print button to allow theuser to print the page for their record.

FIG. 30 is an example client-side display 3000 of a page of anapplication run on computing device 240, showing patient data tab 2910selected and graph view option 2920 selected. Display 3000 may be verysimilar to display 2900, showing the panels 2970, 2972, 2974 and 2976,as well as buttons 2982 and 2984. Graph 3010 is displayed, showing daysof treatment 3020 on the x-axis and intensity of treatment 3030 on they-axis. The user may be able to change the days 3020 visible by movingslide 3040 to shift the portion of the x-axis that is visible.

FIG. 31 is an example client-side display 3100 of a page of anapplication run on computing device 240, showing treatment settings tab2912 selected. In some embodiments, display 3100 has start treatmentlevel panel 3110 allowing the user to adjust the start treatment levelusing buttons 3115. Some embodiments have treatment length panel 3120,allowing the user to adjust the length of treatment using buttons 3125.Display 3100 may further include toggle 3130 to allow the user to put asafety lock or control lock on the device. This causes device 100 tooperate in “control lock mode” and limits the maximum treatment levelthat can be reached, as discussed further above with reference to FIG.7. Display 3100 may include a graphic representation 3140 of device 100,showing the treatment level and treatment length selected on therepresentation of LCD 130. Display 3100 may further include refreshbutton 3150 for refreshing the display, and save button 3160 for savingthe setting to apply to device 100.

FIG. 32 is an example client-side display 3200 of a page of anapplication run on computing device 240, showing device setup tab 2914selected. Display 3200 includes text box 3210 where a clinician canenter an identifier, such as their name, which may be used forauthorisation and/or reporting purposes. The menu may also show a deviceserial number 3220 and firmware version 3230 of firmware 400 of device100 that is plugged into the computing device 240 on which theapplication is being run. Firmware 400 may be updatable by uploading anew firmware file using file browser 3240. Once the desired file isselected, the firmware may be updated by selecting update button 3250.Display 3200 may also include refresh button 3260 to refresh thedisplay, and save button 3270 to save the desired settings.

In some embodiments, the user of the application may be able to adjustaspects of the stimulation signals such as the duty period, duty cycle,sweep delta minimum, sweep delta maximum, sweep period, switching mode,and output switch over frequency values. This enables a wide variety ofstimulation signals and electrode switching patterns to be set upthrough the application running on computing device 240 as required.

In some embodiments of system 200, electrode connectors 226 and 236 maybe arranged in upper and lower banks of electrode connectors. Forexample, there may be two electrode connectors in the upper bank and twoin the lower bank on each electrode connector assembly 220 and 230, suchthat when the device is worn, the upper electrode connectors sit againstthe patient's upper abdomen and the lower bank electrode connectors siton the patient's lower abdomen. In this case, device 100 may beconfigured to enable the stimulation signals on the lower bank ofelectrodes for 15 minutes, then on the upper bank for 15 minutes,followed by 15 minutes on the lower bank and finishing with 15 minuteson the higher bank. These configurations can be changed to any othercombination of stimulation patterns through firmware 400. For example,in some embodiments, device 100 may activate the upper bank ofelectrodes first for a first set period, and subsequently activate thelower bank for a second set period, which may be the same or differentfrom the first set period. The stimulation periods can be adjusted to belonger or shorter in duration as required. In some embodiments,electrodes may alternatively be configured in left and right banks, suchthat device 100 may be configured to activate only the right bank ofelectrodes, only the left bank, or to switch between right and leftbanks.

In some alternative embodiments of system 200, there may only be asingle bank of electrodes, and the device may be worn so that theelectrodes are placed on either the upper or the lower abdomen of thepatient.

FIG. 33a shows a top view of a cable connector 224 or 234. Althoughsystem 200 has a back cable connector 224 and front cable connector 234,only one cable connector is illustrated for simplicity. Back and frontcable connectors 224 and 234 may each have a shaped gripping portion3310 and connector pin 3320. Shaped gripping portion 3310 may be mouldedof plastic or otherwise formed to a size and shape for easy manualhandling. The shape may be designed to be fitted to the exterior of theexternal housing of device 100, such that when connectors 224 and 234are inserted into connector inputs 160 and 165, gripping portion 3310limits the degree of movement of connector 224 or 234 with respect todevice 100 about the insertion axis of connector 224 or 234. Device 100may have a recessed area around each connector input 160 and 165 toreceive and couple with a part of the exterior of gripping portion 3310that is adjacent the connector pin 3320. In some embodiments, back andfront cable connectors 224 and 234 may be identical in shape, allowingeither connector to be plugged into either connector input 160 or 165.In some embodiments, back and front cable connectors 224 and 234 may bemirror images of each other, or otherwise different in shape, with eachrecess on the housing of device 100 coupling only to one of connectors224 or 234, to prevent each connector 224 or 234 from being plugged intothe wrong connector input 160 or 165.

Connector pin 3320 may be an electrically conductive pin to be receivedand to electrically couple with connector input 160 or 165. In someembodiments, connector pin 3320 may have 4 separate electricallyisolated signal channels. In some such embodiments, connector pin 3320may be a 4-pole pin. In some embodiments, connector pin 3320 may have 2,3, 5, 6, or another number of electrically isolated signal channels.Where connector pin 3320 is a 4-pole pin, it may have isolatedconductive sections 3321, 3322, 3323 and 3324. These may be orderedalong pin 3320 in a way designed to reduce the risk of danger throughthe accidental short circuiting of conductive sections. For example, theconductive sections may be arranged such that any two adjacentconductive sections will not be active simultaneously. This safetyfeature is further described in reference to FIG. 34.

FIG. 34 is a diagram of the signal path channels 3400 of the device ofFIG. 1. As described with reference to FIG. 2 above, output stage 380 ofdevice 100 drives output transformers that supply current to electrodeconnectors 226 and 236. In some embodiments, the transformers mayinclude four transformers 3431, 3432, 3433 and 3434, one for eachback/front electrode pair. These may be divided into lower transformerbank 3410, having transformers 3431 and 3432, and upper transformer bank3420 having transformers 3433 and 3434. Each transformer output may besplit into an “a” and “b” line. The output signals from each transformermay be passed through connectors 224 and 234 and onto electrodeconnector assemblies 220 and 230. In some embodiments, all “a” lines arepassed to front connector 224, while all “b” lines are passed to backconnector 234. Where connectors 224 and 234 are 4-pole pin connectors,the lines coming from transformers 3431, 3432, 3433 and 3434 may bearranged such that lines coming from lower transformer bank 3410 are notadjacent each other on the conductive pin portion.

In some embodiments, connector 224 may have conductive pin sections 3441a, 3442 a, 3443 a and 3444 a, and connector 234 may have conductive pinsections 3441 b, 3442 b, 3443 b and 3444 b. These may be arranged asshown in FIG. 34, such that conductive pin sections 3441 and 3442 arenot adjacent, and conductive pin sections 3443 and 3444 are notadjacent. Conductive pin section 3441 a, 3442 a, 3443 a and 3444 a maybe electrically coupled to lines 3431 a, 3432 a, 3433 a and 3434 a,respectively. Conductive pin section 3441 b, 3442 b, 3443 b and 3444 bmay be electrically coupled to lines 3431 b, 3432 b, 3433 b and 3434 b,respectively. In some embodiments, lower transformer bank 3410 and uppertransformer bank 3420 are never active simultaneously. This results in asituation whereby as connectors 224 and 234 are inserted into connectioninputs 160 and 165, there is a reduced chance of a short circuit acrosstwo active signal lines.

Connector 224 is electrically coupled with front electrode connectorassembly 220, having electrode connector portions 3451 a, 3452 a, 3453 aand 3454 a. In some embodiments, conductive pin section 3441 a, 3442 a,3443 a and 3444 a may be electrically coupled to electrode connectorportions 3451 a, 3452 a, 3453 a and 3454 a, respectively. Connector 234is electrically coupled with back electrode connector assembly 230,having electrode connector portions 3451 b, 3452 b, 3453 b and 3454 b.In some embodiments, conductive pin section 3441 b, 3442 b, 3443 b and3444 b may be electrically coupled to electrode connector portions 3451b, 3452 b, 3453 b and 3454 b, respectively.

For each electrode connector assembly 220 or 230, signals coming fromlower transformer bank 3410 appear on electrodes placed in the lowersection of electrode connector assembly 220 or 230, while signals comingfrom upper transformer bank 3420 appear on electrodes placed in theupper section of electrode connector assembly 220 or 230. Therefore, insome embodiments, when worn on the human body front and back electrodeconnector assemblies 220 and 230 provide stimulation to the uppersection of the patient's abdomen or the lower section of the patient'sabdomen at any given time, but cannot stimulate both simultaneously. Asdescribed above with reference to FIG. 32, device 100 may be configuredto provide stimulation to both upper and lower electrode sets byswitching the active transformer bank between activating lower bank 3410and upper bank 3420. This switching may be done periodically (e.g. every10 to 20 minutes), or after a programmed interval (e.g. after about 10,15, 20, 25, 30, 35, 40, 45 or 50 minutes).

In some embodiments, microcontroller 355 of device 100 may be configuredto control the generation and delivery of interferential currentstimulation signals to different pairs of electrodes that include anyelectrode to which back electrode connector assembly 220 is connected incombination with any electrode to which front electrode connectorassembly 230 is connected. For example, microcontroller 355 may beconfigured to control the generation and delivery of stimulation signalsbetween an electrode electrically connected to the top left of backelectrode connector assembly 220 and an electrode electrically connectedto the bottom right of front electrode connector assembly 230. Inanother example, device 100 may be configured to deliver stimulationsignals to an electrode electrically connected to the top left of backelectrode connector assembly 220 and an electrode electrically connectedto the bottom left of front electrode connector assembly 230simultaneously. Alternatively, any other pair of electrodes, wherein oneelectrode is selected from each of the electrodes electrically connectedto back electrode connector assembly 220 and front electrode connectorassembly 230, may be controlled by microcontroller 355 to deliverstimulation signals based on stored configuration parameters in device100. This may be done by providing stimulation signals to a pair ofconductive pin sections, wherein one conductive pin section is selectedfrom connector 224 and one conductive pin section is selected fromconnector 234. In use, two such selected electrode pairs may receiveinterferential current stimulation signals from the stimulation device100 and apply these signals transcutaneously across parts of the lowerabdomen/pelvis and lumbar/sacral region.

FIGS. 35a, 35b and 35c show top, perspective and end views of analternative cable connector 3524 or 3534 for use in system 200. Althoughsystem 200 has a back cable connector 224 and front cable connector 234,only one cable connector 3524/3534 is illustrated in FIGS. 35a, 35b and35c for simplicity. Back and front cable connectors 3524 and 3534 mayeach have a shaped gripping portion 3510 and connector plug portion3520. Connector plug portion 3520 may be an electrically conductive plugportion to be received in and to electrically couple with a recess 3620of socket 3610 (see FIG. 36a ) within connector inputs 160 or 165.Socket 3610 may be configured to cooperate with the connector plugportion 3520 to electrically couple the electrode connector assembly220, 230 to the stimulation generation device 100.

Shaped gripping portion 3510 may have a curved shoulder portion 3515shaped to be received in a recessed portion 3615 of socket 3610 ofdevice 100. In some embodiments, the gripping portion 3510 comprises asubstantially flat base portion 3530 and a rounded or curved surfaceportion 3540 and is configured to cooperate with a correspondinglyshaped recessed portion 3615 of socket 3610. Socket 3610 may be recessedinto a corner of stimulation device 100.

Connector plug portion 3520 may extend out of the gripping portion 3510and contain a series of hollow pin port plugs 3525. Each pin port plugmay form part of a separate electrically isolated signal channel. Insome embodiments, device 100 may have 2, 3, 4, 5, 6, or another numberof electrically isolated signal channels, each corresponding to a pinport 3525.

In some embodiments, the connector plug portion 3520 may be a four pinport plug and each pin port 3525 may be associated with and arranged toelectrically couple to a respective pin 3625 positioned within recess3620 of socket 3610 of the stimulation generation device 100 to therebyallow transcutaneous electrical stimulation to be delivered to theelectrode connector assembly 220, 230.

Pin ports 3525 may be arranged linearly along a latitudinal axis of theconnector plug 3520. Alternatively, pin ports 3525 may be aligned alonga longitudinal axis of the connector plug 3520. In other embodiments,pin ports 3525 may be arranged in any suitable configuration, forexample, in a square or circular formation.

In some embodiments, the connector plug portion 3520 may comprise afront face 3550 and the pin ports 3525 may extend through the front face3550. Connector plug portion 3520 may include a notch 3560 for aligningconnector plug portion 3520 with a corresponding projection 3660 inrecess 3620 of socket 3610. In this way, the connector plug portion 3520may be received by the socket 3610 only when it is orientated correctly.

A successful treatment of a patient by administration of transcutaneouselectrical stimulation treatment delivered using the device 100 of someof the described embodiments is one that may include at least one ormore of the following features: (a) number of defecations have increasedper week; (b) the number of soiling incidents decreased; (c) reduced useof laxatives; (d) changes in the consistency of the stool from hard toincreased softness; and (e) increase in sensory awareness of urge todefecate. Studies involving some described embodiments are described bythe following non-limiting prophetic example.

EXAMPLE 1

The Use of a System for Delivering Transcutaneous Electrical Stimulationin the Treatment of Individuals with a Faecal Waste EliminationDysfunction Condition

Patient Group: Includes individuals suffering from faecal wasteelimination dysfunction of the gastrointestinal tract that have failedto respond significantly to medical treatments such as dietarymodifications, oral and rectal laxatives. Given the diversity of humanbody shapes, individuals participating will be of a variety of bodyshapes and sizes associated with weight, age, ethnicity and gender.

Stimulation Regime

a) The Setting of the Device by a Clinician or Trained Health CareProfessional

The device 100 forms part of system 200, which is designed to be set upfor each patient by a health care professional or someone trained in itsuse. The device 100 has variable settings within the software that allowthe clinician to select the length of treatment time (30 or 60 minutesstandard settings). On the device 100, there are buttons to turn thedevice on/off, to change the current (mAs, level) delivered, and tochoose between audible or non-audible alarms.

The clinician, or treating physician will determine the initialstimulation level for the patient; both children, and/or adults withfaecal waste elimination dysfunction of the gastrointestinal tract. Thestimulation device 100 can deliver current from 0 to 30 mAmps over a 1KΩ load and the level for initial use will be chosen with thestimulation system attached to the individual and turned on. The levelwill be turned up stepwise (incrementally) by the clinician and/orindividual until the highest comfortable level is reached. The patientwill feel tingling under the electrodes and can indicate when thetingling begins to become uncomfortable. The device has a function thatallows the clinician to set this level, which is the individual's“start-level”.

b) The Use of the Device by the Individual Patient for the Treatment ofFaecal Waste Elimination Dysfunction

On subsequent uses, when the device 100 is turned on and the electrodesare connected, the treatment level will rise from 0 to the “start level”at a comfortable rate. The patient can then use the device 100 on thislevel or increase or decrease the stimulation intensity by pressingbuttons 180, 185.

The device 100 also has a control lock. With this activated, the patientcan only turn the device up or down 3 levels, which may be 3 mA levelsin some embodiments, depending on the patient impedance. This is for usewith patients who would fiddle with the device and could turn it up toohigh or turn it off (young children, hyperactive children, adults withattention disorders etc).

Generation and transmission of stimulation signals will be controlledand monitored by the device 100. The stimulation parameters include avariety of times of stimulation: 30 or 60 minutes per day for at leastthree or at least four times a week (preferably every day) or greaterfor a minimum of 2 months. During the stimulation period, theparticipants will be encouraged to continue to perform “normalactivities” of daily life which may include a range of movements fromstanding to sitting or gentle play activities. Patients can increase thecurrent level at each sitting to the maximum tolerated (unless thecontrol lock has been activated).

If stimulation is interrupted during the treatment session, the device100 will recommence at the interrupted time and at the last levelsetting when reattached or turned back on and deliver the stimulationfor the remaining part of the set stimulation period.

The device 100 connects via two cable leads 222, 232 to eight electrodepads 214, 218. The wires in cables 222, 232 leading to the electrodes ofthe accompanying delivery device 100 are separate and fixed within asilicon shell to ensure the arrangement of leads to deliver current tostandard positions (upper front left, upper front right, lower frontleft, lower front right, upper back left, upper back right, lower backleft and lower back right). The device 100 has sensor circuits todetermine if the stimulation currents are flowing. If the current is notflowing, the device indicates a ‘pad fault’ and displays the site of thefault (8 pads, upper front left, upper front right, lower front left,lower front right, upper back left, upper back right, lower back leftand lower back right). If a pad fault is detected, the device willreduce the current to a low level and emit a notification (audibleand/or vibration) until the connection is established. Once all pads areconnected to the leads and the connection to the skin is determined tobe sufficient, the device 100 will ramp the current back up to the‘start level’.

The device 100 will automatically turn off after the set stimulationperiod has elapsed. The device 100 will give a notification (audibleand/or vibration) just before it turns off. The device 100 will displaya symbol to remind the patient to recharge the device 100. The device100 has a rechargeable battery and this must be recharged between uses.

The device 100 records the amount of time it was run for, the date andthe highest level used. The device records these measures for apredetermined period of time, which may be in the order of 90 days, 180days, or 3 years in some embodiments. The clinician can download thisdata via a USB or wireless link to the computer. The data is displayedin calendar and graph form with a summary of the number of days used(out of days elapsed), to give the clinician data to assess compliancewith the treatment schedule and the treatment levels used.

c) Treatment Assessment

As the purpose of this device 100 and system 200 is to treat individualswith faecal waste elimination dysfunction, to determine benefits of thisdevice the patient is also provided with a continence diary to record:defecations (time and amount), whether the defecation was in response toan urge to defecate, occurred while sitting on the toilet at presettimes, the consistency of the stool (hardness and softness) and soilingincidents, the amount of medication (laxatives) and number of incidentsof soiling. The daily dairy can be filled in for each day during theperiod of transcutaneous electrical stimulation. The treatingclinician/physician may during the treatment period or after thetreatment period review the both the continence diary and thestimulation records which will include the actual length of time ofstimulation and the number of times the stimulation was used and thedays used.

A successful treatment is one that includes at least one or more of thefollowing features (a) number of defecations have increased per week,(b) the number of soiling incidents decreased, (c) reduced use oflaxatives, (d) changes in the consistency of the stool from hard toincreased softness and (e) increase in sensory awareness of urge todefecate.

The level of stimulation as pre-set by the clinician at the initialconsultation and a non-changeable parameter by the patient will also benoted. On review of the outcome, the stimulation program and therecorded results, the treating clinician may choose to alter parametersfor further treatment.

It will be appreciated by persons skilled in the art that numerousvariations and/or modifications may be made to the above-describedembodiments, without departing from the broad general scope of thepresent disclosure. The present embodiments are, therefore, to beconsidered in all respects as illustrative and not restrictive.

What is claimed is:
 1. A device for generating transcutaneous electricalstimulation to treat constipation, the device comprising: circuitryconfigured to generate transcutaneous interferential current stimulationsignals; at least one first signal output component for electricallyconnecting the circuitry to a first bank of stimulation electrodes thatare configured to deliver the transcutaneous interferential currentstimulation signals between a front of a torso of a user and a back ofthe torso of the user; and at least one second signal output componentfor electrically connecting the circuitry to a second bank ofstimulation electrodes that are configured to deliver the transcutaneousinterferential current stimulation signals a between the front of thetorso of the user and the back of the torso of the user; and wherein thedevice is configured to: deliver the generated transcutaneousinterferential stimulation signals to the first bank for a first setperiod of time, and subsequent to the first set period of time todeliver the generated transcutaneous interferential stimulation signalsto the second bank for a second set period of time when the first andsecond signal output components are electrically connected to therespective first and second banks of the stimulation electrodes; andallow adjustment of electrical stimulation parameters of the device torestrict the generated transcutaneous interferential stimulation signalsto a current intensity, treatment session duration and frequency of userof the device that are less than, respectively, a maximum possiblecurrent intensity, a maximum possible treatment session duration and amaximum possible frequency of use of the device.
 2. The device of claim1, wherein the transcutaneous stimulation signals are interferentialcurrent stimulation signals for application to a front body regionincluding the lower abdomen and pelvic area and a back body regionincluding the lumbar and sacral area.
 3. The device of claim 1, whereinthe first and second signal coupling components each define respectivesockets for receiving a mating jack of respective electrode connectorsand for transmitting stimulation signals across at least four channels.4. The device of claim 1, wherein the device is substantially free ofexternal user operatable controls, other than a means of turning thedevice on an off, a means to control the strength of the transcutaneousstimulation signals, and a means to turn on and off a sound generatingcomponent.
 5. The device of claim 1, wherein the device comprisescommunication circuitry configured to allow communication with anexternal computing device.
 6. The device of claim 5, wherein the deviceis configured to allow configuration of the electrical stimulationparameters of the device by the external computing device via thecommunication circuitry.
 7. The device of claim 6, wherein theelectrical stimulation parameters further include a sequence ofelectrode pairs to which the transcutaneous electrical stimulation is tobe applied.
 8. The device of claim 1, further comprising isolationcircuitry to electrically isolate a power supply unit of the device fromthe signal output components.
 9. The device of claim 1, wherein thedevice further comprises a microcontroller, a memory unit and at leastone user interface component.
 10. The device of claim 9, wherein thedevice is configured to deliver the transcutaneous electricalstimulation according to at least one stored configuration parameterstored in the memory unit.
 11. The device of claim 1, wherein the deviceis configured so that, when commencing the transcutaneous electricalstimulation, the current of the stimulation is initially zero and isautomatically increased over time until it reaches the restrictedcurrent intensity.
 12. The device of claim 1, wherein the device isconfigured to monitor an impedance between pairs of output terminals ofthe first and second signal output components, and to produce a padfault signal when the impedance is above a predetermined thresholdlevel.
 13. The device of claim 1, wherein the device further comprisesmeans to generate at least one of visual, aural, and tactilenotifications.
 14. The device of claim 1, wherein: the first signaloutput component comprises a first four pole electrical connector part;the second signal output component comprises a second four poleelectrical connector part; and the device further comprises a controllerconfigured to deliver the generated transcutaneous interferentialstimulation signals to the first bank for the first set period of time,and subsequently to the second bank for the second set period of time,by selectively controlling output of the stimulation signals to selectedpairs of poles across the first and second four-pole electricalconnector parts, wherein each selected pair of poles comprises one polefrom the first four-pole electrical connector part and one pole from thesecond four-pole electrical connector part.
 15. The device of claim 1,wherein the first bank of stimulation electrodes comprises an upper backof electrodes, and the second bank of stimulation electrodes comprises alower bank of electrodes.
 16. The device of claim 1, wherein the firstbank of stimulation electrodes comprises a left bank of electrodes, andthe second bank of stimulation electrodes comprises a right bank ofelectrodes.
 17. A stimulation device for transcutaneous electricalstimulation to treat constipation, the device comprising: a housinghaving a first end and an opposite second end; circuitry configured togenerate transcutaneous stimulation signals; and first and second signalcoupling components for connection of the circuitry to respectiveelectrode connectors to deliver the transcutaneous stimulation signalsbetween a front of a torso of a user and a back of the torso of the uservia first and second banks of electrodes, wherein the device isconfigured: to deliver the transcutaneous stimulation signals to thefirst bank and subsequently to the second back; and to allow adjustmentof electrical stimulation parameters of the device to restrict thegenerated transcutaneous interferential stimulation signals to a currentintensity, treatment session duration and frequency of use of the devicethat are less than, respectively, a maximum possible current intensity,a maximum possible treatment session duration and a maximum possiblefrequency of use of the device, and wherein each of the first and secondsignal coupling components is located at the first end of the housing,wherein the first signal coupling component has a first coupling axisand the second signal coupling component has a second coupling axis, andwherein the first and second coupling axes are disposed at an anglerelative to each other.
 18. The device of claim 17, wherein the angle isbetween about 120° and about 60°.
 19. The device of claim 18, whereinthe angle is between about 100° and about 80°.
 20. The device of claim19, wherein the angle is about 90°.
 21. The device of claim 17, whereinthe housing first end comprises first and second opposed corner portionsand first and second coupling axes extend through the first and secondcorner portions.
 22. The device of claim 21, wherein the first andsecond corner portions define respective recesses for receiving at leasta part of respective electrode connectors.
 23. A stimulation device forgenerating transcutaneous electrical stimulation to treat constipation,the device comprising: a housing having a first end and a second end; ascreen display; circuitry configured to generate transcutaneousstimulation signals; first and second signal coupling components forconnection of the circuitry to respective electrode connectors todeliver the transcutaneous stimulation signals between a front of atorso of a user and a back of the torso of the user via first and secondbanks of electrodes, wherein the device is configured: to deliver thetranscutaneous stimulation signals to the first bank and subsequently tothe second bank, the coupling components being at the first end of thehousing; and to allow adjustment of electrical stimulation parameters ofthe device to restrict the generated transcutaneous interferentialstimulation signals to a current intensity, treatment session durationand frequency of use of the device that are less than, respectively, amaximum possible current intensity, a maximum possible treatment sessionduration and a maximum possible frequency of use of the device; and acoupling portion, to couple the device to a wearer, the coupling portionbeing connected to the housing at the first end, wherein the couplingportion allows the device to hang in an inverted position in which thedisplay is upside-down so that when the second end of the device ispivoted upwardly away from the wearer, the display is right-side-up fromthe wearer's perspective.
 24. The device of claim 23, wherein the firstsignal coupling component has a first coupling axis and the secondsignal coupling component has a second coupling axis, and wherein thefirst and second coupling axes are disposed at an angle relative to eachother.
 25. The device of claim 24, wherein the angle is between about120° and about 60°.
 26. The device of claim 23, further comprising usercontrols at the second end.
 27. The device of claim 23, wherein thecoupling portion comprises a clip.
 28. The device of claim 23, whereinthe coupling portion cooperates with a receiving portion of an electrodecarrier to allow the device to be pivoted so that the second end can beswung from below the first end upwards and away from the body of thewearer.